Hansen's Sea Shell Game

Guest Post by Willis Eschenbach

There’s an old con game that has been played on the suckers for hundreds and hundreds of years. It is done in various forms, with various objects, under various names—three card monty, the shell game, Thimblerig, bottle caps, cups and ball, the game is the same in every one. The essence is, the con man puts a pea under a shell, then switches the shells around and asks which shell is hiding the pea.

Figure 1. The Conjuror, by Hieronymus Bosch, painted 1475-1480. The type of tricks the conjuror is doing are thought to be among the origins of the shell game.

I bring this up because our favorite conjuror, James Hansen, is up to his old tricks again. He has a new paper out, Paleoclimate Implications for Human-Made Climate Change, And as always, you have to figure out which shell is hiding the pea.

Here is his money graph, the one that is getting lots of play around the blogosphere. The main observation I’ve seen people making is that having been bitten by previous failed prognostications, Hansen is taking the well-tested Nostradamus route now, and is predicting sea level rise for when he’ll be 137 years old or so …

Figure 2. Hansen’s Figure 7: ORIGINAL CAPTION: “Five-meter sea level change in 21st century under assumption of linear change and exponential change (Hansen, 2007), the latter with a 10-year doubling time.”

Folks are saying that the bad news is, it looks like we won’t be able to tell until 2040 or so if Hansen’s claim is true. But that’s not the case at all. Those folks are not keeping close enough watch on the pea.

In the paper Hansen says:

Sea level change estimates for 21st century. 

IPCC (2007) projected sea level rise by the end of this century of about 29 cm (midrange 20-43 cm, full range 18-59 cm). These projections did not include contributions from ice sheet dynamics, on the grounds that ice sheet physics is not understood well enough.

Rahmstorf (2007) made an important contribution to the sea level discussion by pointing out that even a linear relation between global temperature and the rate of sea level rise, calibrated with 20th century data, implies a 21st [century] sea level rise of about a meter, given expected global warming for BAU greenhouse gas emissions. …

… Hansen (2005, 2007) argues that amplifying feedbacks make ice sheet disintegration necessarily highly non-linear, and that IPCC’s BAU forcing is so huge that it is difficult to see how ice shelves would survive. As warming increases, the number of ice streams contributing to mass loss will increase, contributing to a nonlinear response that should be approximated better by an exponential than by a linear fit. Hansen (2007) suggested that a 10-year doubling time was plausible, and pointed out that such a doubling time, from a 1 mm per year ice sheet contribution to sea level in the decade 2005-2015, would lead to a cumulative 5 m sea level rise by 2095.

The short version of that is:

• The IPCC predicts sea level rise of about a foot (30 cm), but they don’t take ice into account.

• Rahmstorf says a linear projection gives about a metre (3.3 feet) of sea level rise.

• Hansen 2007 says there’s a missing exponential term in Rahmstorf’s work, because the ice will be melting faster and faster every year.

OK, so Hansen 2011 rests on the claims made in Hansen (2007), which turns out to be Scientific reticence and sea level rise. At the end of Section 4 Hansen says that Rahmstorf estimates a 1-metre sea level rise, but that a non-linear ice melting term should be added to the Rahmstorf rise.

Under BAU [“Business As Usual”] forcing in the 21st century, the sea level rise surely will be dominated by a third term: (3) ice sheet disintegration. This third term was small until the past few years, but it is has at least doubled in the past decade and is now close to 1 mm/year, based on the gravity satellite measurements discussed above. …  As a quantitative example, let us say that the ice sheet contribution is 1 cm for the decade 2005–15 and that it doubles each decade until the West Antarctic ice sheet is largely depleted. That time constant yields a sea level rise of the order of 5 m this century.

So to get the final Hansen projection, we need to see what is happening in Rahmstorf, A Semi-Empirical Approach to Projecting Future Sea-Level Rise, paywalled, where we find the following graph of projected sea level rise.

Figure 3. The Rahmstorf estimate of sea level rise, to which Hansen says an exponentially growing ice term should be added.

ORIGINAL CAPTION: Past sea level and sea-level projections from 1990 to 2100 based on global mean temperature projections of the IPCC TAR. The gray uncertainty range spans the range of temperature rise of 1.4° to 5.8° C, having been combined with the best statistical fit shown in Fig. 2. The dashed gray lines show the added uncertainty due to the statistical error of the fit of Fig. 2. Colored dashed lines are the individual scenarios as shown in (1) [Ref. 1 is the IPCC TAR Bible, no page given]; the light blue line is the A1FI scenario, and the yellow line is the B1 scenario.

(In passing, let me again protest the use of the entire IPCC Third Annual Report, thousands of pages, as a reference without giving us chapter and verse in the way of page numbers. My high school science teacher would have slapped my hand for that, it’s a joke.)

The upper blue line is the one that gives us about a meter of sea level rise. So I took that as Rahmstorf’s 1 metre rise. To that I added, as Hansen claims we should, an amount that starts at 0.5 cm in 2000 and doubles every ten years. This is following Hansen’s claim that the non-linear ice disintegration is a separate term that starts small but will “come to dominate” the sea level rise over the century. The result is shown in Figure 4.

Figure 4. Rahmstorfs predicted rise (blue), Hansen’s projected additional rise from “non-linear ice disintegration” (dark red), and total sea level rise (green) predicted in H2011. I have included the last century’s rise of 16 cm, as calculated by Rahmstorf, in the lower right corner for comparison purposes. IMAGE SOURCE

OK, so what Hansen is actually predicting is the green line. However, his real forecast is actually much worse than that. Hansen again, emphasis mine:

The eventual sea level rise due to expected global warming under BAU GHG [greenhouse gas] scenarios is several tens of meters, as discussed at the beginning of this section.

I’m going with “several tens” to mean more than two, so he’s predicting a 30 metre sea level rise!!! … I guess he figured nobody paid any attention when Al Gore threatened us with a 20 metre sea level rise, so he’d better pull out all the stops and give us a real scare, something to make us shake in our panties.

There is a bit of good news, however. Both the Rahmstorf and the Hansen projections are already way above the reality. Since 1993, when the satellites started measuring sea level, we’ve gone up about 4.6 cm (1993-2011). Rahmstorf’s projection is 6.4 cm for that time period, about 40% too high already. Hansen’s larger projection is 7.2 centimetres rise over that time, or 55% too high.

The annual rise is also entertaining. According to the satellites, the trend 1993-2011 was 3.2 mm/yr, and has been declining recently. The change 2009-2010 was under a mm, at 0.9 mm/yr. And 2010-2011 was just about flat.

In 2010-2011, Rahmstorf’s projected rise is already 4.5 mm/yr, about fifty percent larger than the actual rate of the last 18 years. And Hansen’s annual rise is even worse, at 5.3 mm per year.

So both in terms of 1993-2011 rise, as well as current annual rise, both Rahmstorf and Hansen are already way above observations. But wait, there’s more.

Hansen’s rate of sea level rise is supposed to be accelerating, as is Rahmstorf’s rate. By 2020 Hansen says it should be rising at 6.3 mm per year, and everlastingly upwards after that. But in fact we’re already way under their supposed rates of annual increase, and the observed rate of rise is declining …

How does Hansen get these nonsensical numbers? Well, he noticed something in the observations.

This third term [melting ice] was small until the past few years, but it is has at least doubled in the past decade …

My high school science teacher, Mrs. Henniger, bless her, thought extending a linear trend into the future was a crime against nature, and I would hesitate to express her opinion on Hansen blithely extending a ~ 7% annual increase for a hundred years. That kind of compound interest turns a centimeter (3/8″) into 5 metres (16 feet). If Dr. Hansen had submitted this nonsense to her, you would not have been able to read it when it came back for the red pencil scribbles.

You can’t do that, folks. You can’t just observe that something has doubled in the last decade, and then extend that exponential growth out for a century. That’s beyond wishful thinking. That’s magical thinking.

Two final points. First, the pea under the walnut shells. Note carefully what Hansen has done. He has claimed that the sea level rise will be “several tens of metres”. This is at least thirty metres, or a hundred feet, of sea level rise.

He seems to be at least somewhat supporting this claim with his Figure 7 (my figure 2). But if you look at the caption, this is not a forecast, a projection, or a scenario of any kind. Instead, this is merely an “approximation” of what a linear sea level rise might look like and what an exponential rise might look like. You know, in case you didn’t understand “linear” and “exponential”. His actual forecast is under another walnut shell somewhere. We know his “Approximation” can’t be a real projection because it shows almost no rise occurring currently, or for some years.

Second, even this doesn’t begin to unravel the errors, deceptions, alarmism, and con games in Hansen’s work. Do you see the guy in the dark vest and the white pants and shirt at the left of Hieronymus’s painting at the top? See what he has in his hand while he’s looking all innocent at the sky? See who it’s chained to? Hansen’s not really the shell game conjurer, that guy’s a piker, he’s not making much money on the game.

Hansen’s the guy in the dark vest with his hand on your pocketbook …

w.

[UPDATE]

Joel Shore observed correctly that Hansen was basing his estimate of a huge sea level rise on paleoclimate date. Joel is right that Hansen claimed the paleoclimate data shows a rise of 20 metres for every 1°C temperature rise. Because of this, Hansen says that a 2°C future temperature rise will give a 40 metre sea level rise.

Let’s take a bit calmer look at what we know. We know that when there is an ice age, a lot of the water in the ocean behaves badly. It goes up on the land as mainly northern hemisphere ice and snow and glaciers. As a result, the sea level drops by a hundred metres or so. The glaciers stay there until the ice age ends, at which point they melt, and the sea level rises again. Since we’re in an interglacial, right now the glaciers are mostly melted.

So I would certainly not expect further warming to have much effect on melting or sea level. The easy ice is all melted, the giant miles-thick Northern Hemisphere glaciers are almost all melted back into the ocean. The rest are hiding mostly on north slopes in northern climes. So where is the meltwater going to come from?

And curiously, what I found out from Joel’s question is that if you know where to look, we can see that the graphs in Hansen’s own paper bear me out. They say the oceans won’t rise. I don’t particularly believe Hansen’s results, but presuming that they are correct for the sake of discussion, then let’s look at his graphs.

Look first at the sea level during the past four interglacial periods. I stuck a ruler on it so you can see what I mean.

As you can see, at the level of detail of their graph the sea level has never been higher than it than it is now.

Now look at their temperature observations and reconstruction:

According to Hansen, temperatures have been as much as 2.5°C higher than at present … but the sea level hasn’t ever been higher than at present.

If Hansen’s claim were true, that a 1°C temperature rise leads to a 20 m sea level rise, we should see sea levels forty metres or more above present levels in Hansen’s graph (b). Look at the scale on the left of graph (b), that’s off the top of the chart.

Instead, we see nothing of the sort. We see much warmer periods in the past, but the sea levels are indistinguishable from present levels. Hansen’s own graphs show that he is wrong. So it appears that Hansen is doing the same thing, he’s extrapolating a linear trend out well beyond the end.

He’s noticed that when warming temperatures were melting the huge glaciers over Chicago, the sea level rose quickly. Unfortunately, he has then extended that trend well past the time when there are no glaciers in Chicago left to melt …

w.

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dyw

In the good old days, when your numerical prediction did not match experimental data, you had to adjust your theory. People like Bernoulli,Faraday, Tesla, Bohr, Oppenheimer, to name a few, abided by this time-tested way of doing science with some small success. Hansen seems to have invented a new way of doing science – NOT ! ( And that is why “climate science” as practiced by alarmists is pretty much an oxymoron. )

Rogelio

Sorry all this is now a waste of time because there is no global warming (or has not been any for 15 years now(. Its official, even UEA admits it LOL

adolfogiurfa

Hansen? or Hansel and Gretel?. Fairy tales or Terror tales like H.P.Lovecraft´s “The Myths of Cthulhu”? (The Lord of Cthulhu came from the darkest depths of the sea)
http://quizilla.teennick.com/user_images/A/AN/ANG/Anglocelt/1144773562_hu-Cthulhu.jpg

Ed MacAulay

That net rise- red line in the figure – Should it be 1900 to 1999?

tokyoboy

Sorry for posting the same data repeatedly, but our sea level has repeated ups and downs for over a century:
http://www.data.kishou.go.jp/shindan/a_1/sl_trend/sl_trend.html

PJB

I just wish that I would live to see the next 10 years AFTER the graph. Sea-level rise of millions of feet as the graph rises asymptotically away… what rubbish.

Has hansen even done a gut check to see if there is even enough H2O on the planet to give us his magical 100 feet of rise? Enquiring minds want to know.

Willis Eschenbach

Ed MacAulay says:
January 29, 2012 at 6:49 pm

That net rise- red line in the figure – Should it be 1900 to 1999?

No, that’s Hansen’s estimate of the upcoming 21st century sea level rise from “nonlinear ice disintegration”.
Thanks,
w.

Surely it’s clear that it is the AGW advocates who are the deniers–deniers of reality, deniers of facts, deniers of the scientific method, deniers of ethical decency.
They’ve been running a long-term grift, but even those expire eventually.
Who, I wonder, will go to jail over this massive multi-billion dollar fraud of the taxpayer?
Anyone? Anyone? Bueller?

gnomish

awesome article, willis!

Willis Eschenbach

Stephan Barski says:
January 29, 2012 at 6:55 pm

Has hansen even done a gut check to see if there is even enough H2O on the planet to give us his magical 100 feet of rise? Enquiring minds want to know.

Yeah, I think there’s enough ice to do that. Antarctica’s ice sheets are huge and thick. He talks about it in one of those papers I cited, I can’t be bothered to figure out where.
w.

There was an interesting discussion in the science media a while ago over Rahmstorf’s “Semi-Empirical Approach” with researchers who measure actual sea level rise quite upset with the strategy. “Semi-empirical” of course means, “my mathematical model tells me”.

A while back I cross posted a question here and at realclimate. In that question, I asked if anyone could show even a bit of math to explain why the ocean is so cold. Without actually posting any math, Dr. Schmidt answered that the reason was evaporative cooling in the high latitudes removed heat from the ocean. That is, the oceans take heat from the tropics (where there is a lot more greenhouse gas) to the arctic / antarctic, (where there is a lot less greenhouse gas), and release that heat into the atmosphere. This is an obvious and major negative feedback. There is a huge amount of heat that should be in the ocean without this effect. Has Dr. Hansen considered the feedback of reduced warming caused by increased ocean surface that naturally follows a decrease in arctic ice cover? For those who are not familiar with the science of radiant heat transfer, the greenhouse gas I’m referring to above is water.

Thanks Willis,
Again, an excellent post!
Now the pickpocket will have to adjust for the cooling since 2001 and still make it scary. 😉
Or maybe he has not noticed it?

Bill Jamison

That’s a great trick Hansen used because he created a projection that can’t be falsified for at least 40 or 50 years!
Well done James!

LOL in Oregon

Hey,
you should be nicer to Mr. Hanson, (Piled High and Deep).
Everyone knows that Einstein’s generation couldn’t read thermometers or record weather information accurately.
Nukes, Quantum mechanics, transistors, relativity, WW II, … sure, the easy stuff.
But determine the temperature, record weather?
Naaah, too hard for those primitive folk!
LOL in Oregon

Hansen’s model is crushed by the evidence of little change in the global total ice anomaly
Furthermore, he provides no evidence to counter the possibility that we may again have ice fairs on the Thames – and the Hudson rivers – in 2030.
This is particularly significant in light of Lucia’s HadCrut Nov: Lowest since…. February. evidence that global warming over the last decade has only been a tenth of what IPCC models predicted from 2000. e.g. 0.02C/decade vs 0.20 C/decade.
Or that HadCrut has actually been on a negative trend for the last decade. since Jan 2001.
An enterpreneurial relative advised on starting a business:

“Figure out how much it will cost, and then triple it.”

Hanson appears to have forgotten to allow for tripling to account the great uncertainty of nature.
As Robert Burns observed:

The best-laid schemes o’ mice an’ men
Gang aft agley,

John F. Hultquist

A few thousand years ago there was glacial ice pushing into what is now called the Strait of Juan de Fuca with ice well below what is now sea level. The Puget Sound area was filled with ice and depressed by the weight. Conditions changed and that ice melted. Remaining ice is at higher elevations and/or higher latitudes. Greenland and Antarctica fit this description. I must have missed the chapter where it says ice melts more readily in naturally cold environments. I’ve never been able to keep track of the pea under the shell, either.

Right on, Willis!
Great post. Thank you.

lectorconstans

There’s models, and there’s parameters in the models. I don’t know about the models, but I assume there are some adjustable parameters. One scientist went to von Neumann with his model, one that seemed to work pretty well.
Von Neumann asked how many variable parameters there were in the model. The scientist replied, “four”.
Von Neumann laughed, told him to take his model away. “With four parameters I can model an elephant. With five I can make his trunk wiggle.”
Like everything, it’s Out There:
http://en.wikiquote.org/wiki/John_von_Neumann
“With four parameters I can fit an elephant, and with five I can make him wiggle his trunk.
Attributed to von Neumann by Enrico Fermi,”

Joel Shore

Willis Eschenbach says:

Two final points. First, the pea under the walnut shells. Note carefully what Hansen has done. He has claimed that the sea level rise will be “several tens of metres”. This is at least thirty metres, or a hundred feet, of sea level rise.
He seems to be at least somewhat supporting this claim with his Figure 7 (my figure 2). But if you look at the caption, this is not a forecast, a projection, or a scenario of any kind. Instead, this is merely an “approximation” of what a linear sea level rise might look like and what an exponential rise might look like. You know, in case you didn’t understand “linear” and “exponential”. His actual forecast is under another walnut shell somewhere. We know his “Approximation” can’t be a real projection because it shows almost no rise occurring currently, or for some years.

Actually, I think that he is basing it on paleoclimate data for past temperatures and past sea levels, which he says implies that the eventual equilibrium sea level rise is about 20 m for each 1 C of global temperature rise. (See, for example, the last paragraph in Section 3.4 and the first page of Section 4.3.)
One might be able to quibble about whether it is really 20 m per 1 C…but I think the general conclusion from the paleoclimate data that the sensitivity of sea level to temperature is very strong seems to be correct. Then the question becomes how fast that sea level rise can be realized.

A physicist

If in the next couple of decades, the sea-level rise accelerates to 6 mm per year, then that will signify (for sure) that the Greenland and/or Antarctic ice sheets have begun melting.
For some reason that I cannot understand, the widespread opinion here on WUWT (and prominently featured recently in the Wall Street Journal), that “Hansen’s predicted acceleration cannot happen”, is called “skepticism.”
But really, isn’t it the WUWT/WSJ belief that “it cannot happen” view the exact opposite of rational skepticism?
Because truly rational skepticism has to say “Yeah, it might happen.”
After all, Hansen and his colleagues have been right twice before, with his 1981prediction that the Northwest Passage would open, and that global temperatures would show a BEST-style hockey-stick.
That’s why rational skepticism has to say “Maybe Hansen is right a third time.”
Time will tell.

Joel Shore

Stephan Barski says:

Has hansen even done a gut check to see if there is even enough H2O on the planet to give us his magical 100 feet of rise? Enquiring minds want to know.

The numbers are roughly these: Greenland has enough land ice to raise sea levels by about 7 m. Greenland and Antarctica together have enough land ice to raise sea levels by about 70m. Of course, most scientists do not believe it very conceivable that we could melt all of the Antarctic ice…but (at least eventually) melting/disintegrating essentially all of Greenland’s ice and some percentage (say, 10-20% ??), of Antarctica’s does seem conceivable.

Bill Marsh

“In 2010-2011, Rahmstorf’s projected rise is already 4.5 mm/yr, about fifty percent larger than the actual rate of the last 18 years. And Hansen’s annual rise is even worse, at 5.3 cm per year.”
Did you mean Hansen to be 5.3mm rather than cm/yr?
[Thanks, it is mm, fixed. —w.]

Based on gravity measurements (from GRACE I presume)? Who is he kidding?
GRACE was just launched recently and there is no way to extrapolate back in time what we have just discovered!
Moroni pseudo science. Hard to swallow we tax payers pay for this crap.

markus

“A physicist says:
January 29, 2012 at 7:45 pm
If in the next couple of decades, the sea-level rise accelerates to 6 mm per year, then that will signify (for sure) that the Greenland and/or Antarctic ice sheets have begun melting.”
You poor, poor man.
“That’s why rational skepticism has to say “Maybe Hansen is right a third time.”
You delusional, delusional man. If you are hard up, contact me, I’m easy to find, and I’ll slip ya a couple of bob for a psychologist.
Markus Fitzhenry

Bill Marsh

A physicist,
I think that the entire point of Willis’ post is to show that Hansen’s prediction isn’t happening, by a large amount, even at this early stage of his prediction. If the prediction, which is based on a rather steep exponential, is substantially off at the early stage, it is most likely off by an exponential amount at the later stages. I don’t think he ever stated it ‘couldn’t happen’, just that it isn’t right now, therefore it most likely won’t happen.

Anything is possible

You’ve got to hand it to climate “scientists”……
A few taps on the keyboard here, a click of the mouse there, and before you know it, entire ice sheets are wiped off the face of the Earth without giving the slightest consideration to how much energy it would actually take….
334KJ to melt 1 litre of ice at 0C is a good place to start………..

Bill Marsh

Seems to me that, back in 1988, Dr Hansen was predicting all sorts of dire consequences for the 2010 era. It appears that all he does, when the dire predictions don’t come to pass, is make even more dire predictions even further into the future.

Freshman year assignment in an intro to engineering course:
Plot the historical population figures for the city of Houston, and for the United States.
We plotted the data on semi-logarithmic paper, because populations tend to grow exponentially & exponential growth plots as a semi-log straight line.
Projections of the trends crossed in 2130, if I recall correctly.
Obviously, by 2130, everyone in the U.S. will live in Houston.

Hansen creates a hypothesis which cannot be tested until long after he will be dead, thus ensuring(so he thinks) that he will not be prosecuted for fraud. This is a desperate attempt at distorting reality. It is my earnest opinion that Hansen is [SNIP: Axel, that may be true, but in this context is just name calling and does not contribute to the discussion. -REP] .

Lew Skannen

So in a couple of centuries the oceans will be expanding out of our galaxy at ten times the speed of light.
CAGW makes supernovae look pretty tame!

Dave Dardinger

Willis,
re: your response to Ed MacAulay’s post. He was not referring to the red curve but the bright red bar which you label as 1990-1999 and should be 1900-1999 which you attribute to Rahmsdorf @ 16 cm which would thus average to 1.6 mm per year, a reasonable amount.

Joel Shore on January 29, 2012 at 7:48 pm said:
——-
The problem with your 10-20 percent melt analyses is the time frame involved. Man might continue burning fossil fuel at most for the next 400 years then it’s back to equilibrium but your projection carries on for thousands of years.

You should have included the final sentence of the Hansen para you quoted which said:
“Of course I cannot prove that my choice of a ten-year doubling time for nonlinear response is accurate, but I am confident that it provides a far better estimate than a linear response for the ice sheet component of sea level rise under BAU forcing.”

Assuming all the sea ice melts is the stuff of climate alarmism:
http://www.johnstonsarchive.net/environment/waterworld.html
[BTW, great article as usual, Willis.]

Robert Austin

A physicist says:
January 29, 2012 at 7:45 pm
.
“After all, Hansen and his colleagues have been right twice before, with his 1981prediction that the Northwest Passage would open, and that global temperatures would show a BEST-style hockey-stick.”
I understand that you think Hansen is a genius of the first order but these vaunted predictions are actually rather pedestrian. The Northwest Passage has been open before in the last century and negotiated by wooden ships without benefit of radar, up to date weather and ice forecasts and satellite navigation, so where is the genius in saying it could be open again. And where did Hansen predict the inverted hockey stick that derives from BEST. You know, the one with the rising handle in the latter part of the 20th century and the horizontal blade in the 21st century. Did Hansen actually predict a temperature plateau from 1998 to present?
Hansen seems to hit bulls eyes with the marksmanship of a Texas sharpshooter.

James of the West

@ A Physicist – healthy skepticism about others claims is to doubt that they are correct if a mounting body of real world evidence points to an alternative conclusion – of course there has to be good reason for the doubt, like for example the real world data on sea level change in this example.
To say that Hansen’s predictions cannot come true in the distant future is not certain because that in itself would be a prediction based on todays unsettled science. Climate change due to factors other than anthropogenic/CO2 could deliver lots more warming by 2100 and have us ice cap free by the end of the century but this is pure speculation on the boundaries of possibility and not a prediction of any rational sort.
We can say that so far (since measurements began) sea level change does not appear to be exponential but the data might (although highly unlikely based on our measurements to date) eventually transition to exponential increases before 2100, you and I will probably never know. It isn’t possible for me to say with certainty that you and I will be dead by 2100 but its highly unlikely we will be alive.

Dave Wendt

A physicist says:
January 29, 2012 at 7:45 pm
If in the next couple of decades, the sea-level rise accelerates to 6 mm per year, then that will signify (for sure) that the Greenland and/or Antarctic ice sheets have begun melting.
If you instantaneously double the present rate and straight line it to the end of the century, you end up with less than two feet, not 20 meters and certainly not 30 meters. And since a number of observed factors suggest that we may be in for up to a couple of decades in which global temperatures may actually decline not rise, we could just as likely see a corresponding decline in GSML for those years. Even if we see warming again in the future when the multidecadal oscillations turn back again, odds are sea levels will be rising from a point lower than the present. Of course, all these suggestions are completely, if not equally, speculative and as you suggest “Yeah, it might happen.” But then, at some point a giant extraterrestrial vessel could appear in orbit above our planet, drop in a straw and suck our planet dry. Hey, it could happen!

grayman

Predictions, Projections, Approxamations, any way you say it it is a GUESS.

Willis Eschenbach

Dave Dardinger says:
January 29, 2012 at 8:39 pm

Willis,
re: your response to Ed MacAulay’s post. He was not referring to the red curve but the bright red bar which you label as 1990-1999 and should be 1900-1999 which you attribute to Rahmsdorf @ 16 cm which would thus average to 1.6 mm per year, a reasonable amount.

Ah, thank you very kindly, you and Ed are correct. I’ll go fix that right now.
w.

TRM

So since the last glacial maximum (~16k BC) the increase sea level is about 400 feet and we are going to do 25% of that in 100 years? Get out the hip waders folks but it isn’t water that you’ll need to protect yourself from it’s the BS Express with conductor Hansen.

u.k.(us)

Joel Shore says:
January 29, 2012 at 7:48 pm=
===========
[SNIP: Policy. -REP]

James Reid from Arding

So it seems to me that this might be one of the centrepiece papers to go into AR5 at the last minute to become a major headline/talking point?
I can just hear the response by my rusted on Labor pals – “Sea levels are going to reach 20 or 30 metres by the end of the century if we repeal Julias carbon tax!”. That is after they have lost the next federal election in Australia (this is my forecast – can’t put error bars on the stats – but if I was a betting person I’d put several houses on it :-).

agw nonsense

I work at sea and live by the sea and I find it all a bit of a yawn.Remember the opposite to being a sceptic is being gullible.The rocks I fished off 30 years ago are still there,the reefs I surfed 30 years ago are still breaking,the weather changes,the seasons change,and the climate has been changing for 4.5 billion years.get a life

pat

The level of sea level rise simply cannot be exponential. Period. Mass, energy, atmospheric volume make this impossible. In fact at some point the seas regress given these CAGW models.

Tom_R

>> A physicist says:
January 29, 2012 at 7:45 pm
After all, Hansen and his colleagues have been right twice before, with his 1981prediction that the Northwest Passage would open, and that global temperatures would show a BEST-style hockey-stick. <<
1. Do you have a reference to the Northwest passage opening? How many ships have traveled through the Northwest Passage? Were there any that weren't either icebreakers or escorted by icebreakers?
2. Using BEST as an example of any prediction is rather humorous. 1/3 of the BEST stations showed a net cooling, and these were well mixed among those showing warming, so it wasn't due to regional differences. BEST proved only that trying to discern a trend from ground stations is foolish.

A physicist

Robert Austin says: The Northwest Passage has been open before in the last century and negotiated by wooden ships without benefit of radar, up to date weather and ice forecasts and satellite navigation, so where is the genius in saying it could be open again.

Robert, you don’t mention where you got that information, but whoever/whatever the source was, definitely no skeptic should ever trust that source again!
Before the 21st century, I believe there is no record of any wooden ship ever making the Northwest passage without over-wintering in the ice at least one year, sometimes two years, or (sadly frequently) never returning at all.
Whereas nowadays ordinary folks are making the NW Passage in rowboats, kayaks, and inflatable rafts.
But hey, even in the “big Arctic thaw” of the 21st century, the NW Passage still has its risks for sailors: sometimes the yogurt goes sour!
With with winter ice presently at record low levels, in both area and thickness, it’s a safely non-skeptical bet there will be more ordinary small-boat folks making the NW Passage in 2012.

WLF15Y

Don’t mean to get off topic but…..
Has anybody seen this “breaking” news that the Met Office and The University of East Anglia just released the temp data that shows no warming since 1997?
The news was “broke” by The Mail Online, so I am hesitant to believe it.
[REPLY: Thanks, but this tip has appeared everywhere today. David Archibald has a very interesting point that he makes here. Thanks again and keep WUWT in mind. -REP]

agw nonsense

I forgot to mention if the average temp in Antarctica is -40 a temp rise of 1 or 2 or even 5 degrees isn’t going to achieve much is it,-35 is still to effing cold.